Spectroscopic and Hydrodynamic Characterisation of DNA‐Linked Gold Nanoparticle Dimers in Solution using Two‐Photon Photoluminescence

Abstract

Two-photon photoluminescence (TPPL) emission spectra of DNA-gold nanoparticle (AuNP) monoconjugates and the corresponding DNA-linked AuNP dimers are obtained by photon time-of-flight spectroscopy. This technique is combined with two-photon photoluminescence fluctuation correlation spectroscopy (TPPL-FCS) to simultaneously monitor the optical and hydrodynamic behaviour of these nano-assemblies in solution, with single-particle sensitivity and microsecond temporal resolution. In this study, the AuNPs have an average core diameter of 12 nm, which renders their dark-field plasmonic light scattering too weak for single-particle imaging. Moreover, as a result of the lack of plasmonic coupling in the dimers, the optical extinction, scattering and photoluminescence spectra of the DNA-AuNP complexes are not sufficiently different to distinguish between monomers and dimers. The use of TPPL-FCS successfully addresses these bottlenecks and enables the distinction between AuNP monomers and AuNP dimers in solution by measurement of their hydrodynamic rotational and translational diffusion.

Nanosurface Energy Transfer from Long-Lifetime Terbium Donors to Gold Nanoparticles

“…Extinction spectra were acquired using a Lambda 35 UV–vis spectrophotometer from Perkin Elmer or on a modular fiber-based spectrometer system (OceanOptics LS-1 white light source and USB4000-VIS–NIR CCD spectrometer). Resonant light-scattering spectroscopy (RLS) of the AuNP and AuNP–Tb-sAv solutions was performed using a fiber-coupled incandescent white light source (AvaLight-HAL-(S)-mini) and an OceanOptics QE65000 spectrograph, at right angle, using our published method, ,, A 200× diluted Ludox solution in 50 mM aqueous NaCl was used as the reference. The corrected light-scattering spectra represent the relative light-scattering cross sections as a function of wavelength.…”

Phosphorus Kβ X-ray emission spectroscopy detects non-covalent interactions of phosphate biomolecules in situ

“…90, 2148.90] and a very mild Whittaker-Eilers smoothing was applied (λ = 4). 62,63 Unless otherwise noted, spectra are presented normalized to a total area of 1000. All data processing was accomplished using in-house python code.…”